In a construction machine including a lower travelling body and an upper slewing body slewably mounted on the lower travelling body, a cab is disposed as an operator's compartment of the construction machine on an upper frame that constitutes the upper slewing body.
Regarding this type of construction machine, there is an important challenge of securing safety of an operator staying in the cab in case of turning over of the construction machine. Specifically, turning over of a construction machine causes an external lateral load to act on the cab to deform it. Required is securing a safety space for the operator, especially a space in a rear portion where the operator stays, even though the cab is deformed.
As means for satisfying the above requirement, Japanese Unexamined Patent Publication No. 2007-69807 discloses a cab for use in a construction machine, the cab including a pair of right and left rear pillars standing in a rear portion of the cab and a rear panel disposed between the pair of rear pillars, the rear panel being given high rigidity. Specifically, the rear panel has a multi-layer structure including a plurality of panel portions joined to each other, at least one of the plurality of panel portions having a reinforcement rib.
Thus thickening rear panel, however, involves increases in material cost and production cost of the rear panel. In addition, the high rigidity given to the rear panel, that is, a high deformation resistance, increases a load that acts on the rear pillar, on the contrary to the expectation, which may bring the rear pillar into breakage. The related art, thus, cannot remarkably improve protection for the operator.